Grain fumigant composition and method



.of grain, seeds, and similar food materials.

United States Patent O f ce GRAIN FUMIGANT COMPOSITION AND METHOD FOR MAKING AND USING SAME Joseph R. Baldridge, Mentor, Ohio, assignor to Diamond Alkali Company, Cleveland, Ohio, a corporation of Delaware No Drawing. Application February 17, 1958 Serial No. 715,485

9 Claims. (Cl. 167-22) This invention relates to new and useful insecticidal compositions and more particularly relates to improvements in grain fumigant compositions and to a method for fumigating insect-infested grain and similar substances.

The control of weevils, bran bugs, and related insect pests is a problem of major importance in the storage In practice, such stored grain is frequently held in bins or elevators for extended periods of time and if untreated, may become so badly infested with the insects as to be of little value.

While a variety of organic compounds has been suggested heretofore and used commercially as grain fumigants, the problem of controlling insect infestation of grain remains a serious one. One of the difliculties in many prior fumigant materials has been their high flammability as evidenced by their low flash points. For example, while carbon disulfide used alone would be an excellent fumigant, as far as its fumigating qualities are concerned, its use is highly impracticable because of its high flammability. Accordingly, in practice, it has been necessary heretofore to formulate a fumigant composition so as to provide a reasonably safe material from the standpoint of fire hazard.

Exemplary of such formulations is a mixture containing about 80% carbon tetrachloride and about 20% carbon disulfide, which formulation has been used extensively in the past and is commonly known in the trade as an 80-20 mixture. Although this mixture, like carbon disulfide alone, is an excellent fumigant as far as its furnigating qualities are concerned, its flash point is sufliciently low so as to present a fire hazard when used.

More recently, it has been proposed to use a mixture containing about 79 parts by volume carbon tetrachloride, about 21 parts by volume carbon disulfide, about 3 parts by volume petroleum ether, and about 1 /2% by weight of the other constituents of sulfur dioxide. Although this formulation has proved to have excellent fumigating qualities and its complete absence of a flash point removes any fire hazard, other difficulties have been experienced in its use.

The presence of sulfur dioxide in the formulation has been found to be at least irritating if not potentially dangerous to the personnel who are working with the formulation, both in its preparation and use, inasmuch as the S is diflicult to put into the formulation and readily escapes during application of the fumigant to the grain. Additionally, the presence of sulfur dioxide in the formulation necessitates that the fumigant be packaged in tightly sealed drums to prevent the escape of S0 vapors, thereby preventing the storage of the fumigant in bulk, i.e., transportation in tank cars or tank trucks to a bulk storage tank, which practice has become increasingly popular in the industry. Moreover, the presence of sulfur dioxide in the formulation presents a corrosion problem in that the sulfur dioxide readily reacts with any oxygen and moisture present to form sulfuric acid which is extremely Patented July 21, 1959 corrosive, readily attacking any metal with which it comes in contact.

It is, therefore, an object of the present invention to provide new and improved grain fumigants which are exceedingly toxic to insect life, even at low concentrations, and which are characterized by a lack of flash point.

A further object of this invention is to provide an improved grain fumigant composition of the above type, which composition is not subject to the disadvantages of corrosion and which is not injurious to the health of those working with it.

A still further object of the present invention is to provide an improved fumigant of the above type, which fumigant may readily be transported in bulk.

These and other objects will become apparent to those skilled in the art from the description of the invention which follows.

In the past, in formulating a grain fumigant composition having no flash point, i.e., one which is substantially non-flammable, it has been believed to be essential to include as a necessary part of this formulation, sulfur dioxide. It has been found that in a fumigant formulation containing carbon tetrachloride and carbon disulfide without sulfur dioxide, even when petroleum ether is present, the formulation still had a flash point sufliciently low to present a fire hazard during its use. It has now been found, in the practice of the present invention, that by reducing the carbon disulfide content from about 20% by volume to within the range of -17 .5% by volume, a fumigant composition can be compounded with carbon tetrachloride, carbon disulfide, and petroleum ether, without sulfur dioxide, which composition has no flash point at temperatures at or above the boiling point of the mixture, while still maintaining a high insect toxicity.

The constituents of the foregoing composition may be the chemically pure compounds or, if desired, such materials as are available commercially. The expression petroleum ether, as used herein, is intended to include such materials falling within the definitions as set forth in Hackhs Chemical Dictionary, third edition, page 635, wherein petroleum ether is described as a mixture of C and C hydrocarbons, the mixture having a boiling point range of approximately 40 60 C., as Well as normal hydrocarbon constituents thereof, i.e., normal pentane and normal hexane.

It has been found in the practice of the present invention, that an excellent grain fumigant formulation, both from the standpoint of fumigating qualities as well as flash point, is formed using 82 8370 by volume carbon tetrachloride, 16.5-17.5 by volume carbon disulfide and .5l% by volume petroleum ether. A preferred fumigant formulation of this type is one having the following composition in percent by volume:

Petroleum ether 0.5

At present, it is not clearly understood just Why the addition of a small amount of petroleum ether to the foregoing binary mixture produces such an elfective fumigant having a complete lack of flash point. However, by way of theory, which is not to be construed as limiting the present invention in any way, it is believed that the petroleum ether exhibits a singular chemical aflinity in a binary solvent blend of carbon tetrachloride and carbon disulfide, serving to eliminate the flash point and the otherwise high flammability of the mixture. Regardless of theory, the addition of the petroleum ether to the abovedescribed mixture does, in fact, produce a synergistic fumigant mixture having no flash point.

The following table, wherein quantities are expressed 3. in terms of percent by volume, illustrates varying compositions and their resulting flash points; the expression flash point" as used herein means the lowest temperature at which the vapors of a liquid may be ignited momentarily 4 as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner, it being intended to cover the invention broadly in whatever form its principle may be by passing a flame over the liquid. Such a test is deutilized. scribed in detail in ASTM Standard D92-52 as the so- What is claimed is: called Cleveland flash cup test. 1. A fumigant composition comprising 82-83% by Table Ingredients 1 2 3 4 5 6 7 8 9 10 11 n-pentane n-hexane 0.5

Flash Point, O No flash 50 0., test d sr'nntimwd 18 10 6 4.5 25.5

From the above table, it can be seen that compositions volume carbon tetrachloride, 16.5-17.5% by volume car- 1-6, which contain 16.5-17.5% by volume carbon disul- 2O bon disulfide and 0.5-1% by volume petroleum ether. fide, exhibit no flash points up to 50 C., which temper- 2. A fumigant composition comprising 82-83% by volature includes the boiling point of the mixture, at which ume carbon tetrachloride, 16.5-17.5% by volume carbon temperature the tests are discontinued. It will be noted disulfide and 0.5'-1% by volume normal pcntane. that the results are not changed whether these composi- 3. A fumigant composition comprising 82-83% by voltions contain petroleum ether, normal pentane or normal ume carbon tetrachloride, 16.5-17.5% by volume carbon hexane. On the other hand, compositions 7, 8 and 9, disulfide and 0.5-1% by volume normal hexane. v which contain an amount of carbon disulfide in an excess 4. A fumigant composition comprising 82.3% by volof 17.5 although also containing petroleum ether, exume carbon tetrachloride, 17.2% by volume carbon dihibit relatively low flash points and hence their use as a sulfide and 0.5% by volume petroleum ether. fumigant involves a fire hazard. Compositions 10 and 5. A fumigant composition comprising 83% by volume 11 illustrate that when the compositions contain no pecarbon tetrachloride, 16.5% by volume carbon disulfide troleum ether, the flash point is extremely low and hence and 0.5% by volume petroleum ether. the composition is highly inflammable. 6. A fumigant composition comprising 82% by volume It has been found that the fumigating qualities of carbon tetrachloride, 17% by volume carbon disulfide, formulations containing 82-83% carbon tetrachloride, and 1% by volume petroleum ether. 16.5-17.5% carbon disulfide, and 0.51% petroleum ether 7. A fumigant composition comprising 82% by volume are excellent, being comparable to those of the 80-20 carbon tetrachloride, 17.5% by volume carbon disulfide mixes, i.e., 80% carbon tetrachloride, 20% carbon disul- 3 and 0.5 by volume petroleum ether. fide, which mixes are well known in the art to be highly 8. The method of fumigating an insect-infested materi eflective fumigants. and space, said method comprising contacting said ma- In practice, fumigants of the present invention may terial and space with a mixture comprising 82.3% by be employed by sprinkling, spraying, or pouring the fumivolume carbon tetrachloride, 17 .2% by volume carbon gant over the grain, seed, or other material to be fumidisulfide and 0.5% by volume petroleum ether. gated in amounts particularly ranging from about 0.5 9. The method of preparing a substantially non-flamgallon to 7.5 gallons per 1000 bushels. The lack of flamimable toxic fumigant comprising the steps of mixing mabih'ty of compositions of the present invention permit 82.3% by volume carbon tetrachloride with 17.2% by safe handling and substantially eliminate fire hazards in volume carbon disulfide and adding thereto 0.5 by volthe fumigation operation. ume petroleum ether to impart substantial non-flamma- While the foregoing description is particularly directed bility to said mixture. to the fumigation of grain and related products, it is to be understood that the novel fumigant products of the References Cited in the file of this Patel!t present invention also may be employed in household fumigation, vault fumigation and the like, Wherever a- UNITED STATES PATENTS highly effective toxicant material is required. 1,134,879 schellel May 30, 1916 While there have been described various embodiments 2,128,433 Rotlleim A g. 30, 1938 of the invention, the methods and products described are 2,803,581 ard Aug- 20, 1957 not intended to be understood as limiting the scope of the invention, as it is realized that changes therein are OTHER REFERENCES possible, and it is further intended that each element Hackhs Chem. Dictionary, The Blakiston Co., 3rd ed.,

recited in any of the following claims is to be understood 

1. A FUMIGANT COMPOSITION COMPRISING 82-83% BY VOLUME CARBON TETRACHLORIDE, 16.5-17.5% BY VOLUME CARBON DISULFIDE AND 0.5-1% VOLUME PETROLEUM ETHER. 